Radio Frequency (RF) transmitters used for wireless communication require high linearity to preserve modulation accuracy and to limit spectral regrowth. Linear amplifiers are capable of electrical efficiency greater than fifty percent when operated at saturation. However, they are generally not operated at an optimal level of efficiency due to the need to provide high linearity. Time varying envelopes present an additional problem. The current industry approach for linear transmission is to back off from the compression point of the amplifier achieving linearity at the expense of efficiency.
A number of alternative architectures have been introduced to improve transmitter efficiency. However, each approach has inherent limitations that have kept them from being widely adopted and implemented except in niche applications. The current industry approach for linear transmission is to back off from the compression point of the amplifier achieving linearity at the expense of efficiency.
Consequently, a need exists for a high efficiency transmitter.